With the advent of many different sizes, shapes and configurations of paperboard or similar type containers, it is well-known in the art to die-cut, strip and blank paperboard box blanks using an automatic sequential press or die-cutting machine. By automating the process and by using computer-aided technology, it is now possible to configure die-cut blanks in a limitless number of dimensions and specifications and, as well, to lay-out any number of blanks on a single sheet of paperboard while automatically cutting, stripping and blanking the sheets with little or no human operator intervention. The typical system and press known in the art is discussed in pending U.S. patent application Ser. No. 07/899,427 filed on Jun. 16, 1992.
The general configuration of automatic die-cutting machines for the production of die-cut blanks is well-known. In particular, a sheet of box blank material, usually paperboard, is automatically interposed or urged by mechanical means beneath the surface of a cutting die as part of the first stage of the process. The cutting die comprises a planar die having specially configured cutting edges created through the use of computer and laser technology to reflect a particular series of die-cut blank lay-outs for cutting. Once a sheet is interposed under the cutting die on a cutting platen, the cutting die is pressed onto the sheet from below thereby causing the sheet to be "cut" or "etched" by the cutting die thereabove.
After the initial cutting process, the entire cut or etched sheet is automatically pulled or urged into a second station of the process for the stripping away of most of the excess material from around the cut box blanks. This is referred to as the stripping station. The stripping process comprises a female stripping tool onto which the cut sheet is automatically interposed. The female stripping tool has a series of configured openings corresponding to the etched portions of the cut sheet and is adapted to receive from above the male stripping tool. The male stripping tool cooperating with the female stripping tool, effectively breaks away and separates from the box blanks the majority of excess material by urging downward onto the sheet arranged over the female stripping tool. It is, of course, critical that the male and female stripping tools are aligned precisely and that the cut sheet is arranged in alignment therebetween to insure that stripping is effectively accomplished without tearing of the box blank, jamming of the machine or damage thereto. Further, precise alignment is required on account of the narrow tolerances necessary to assemble the box or container formed from the cut sheet.
On machines so configured in the generally known process, the stripped sheet is next urged in between yet another series of male and female blanking tools arranged one above the other, again required to be in precise alignment. The female blanking tool is adapted to receive thereabove the die-cut blank stripped at the previous station and has a series of openings directly corresponding to the shapes of the cut boxes to be blanked. In turn, the corresponding male blanking tool of similar contour to that of the female tool is adapted to push the cut box blanks free from any remaining extraneous material and through the female blanking tool into a stack therebelow. Accordingly, it is once again required that the male and female blanking tools be carefully aligned and that the sheet to be blanked is precisely arranged therebetween to avoid problems similar to those described in the stripping portion of the operation. After blanking is completed, the remaining extraneous material is then urged off the face of the female blanking tool into a refuse area and the process continues from the beginning.
In normal operation of the box blank die-cutting machines, each of the tools is interposed one above the other in the machine at each station. In general, the tools are slided into the machine or press from the side and locked into position using a series of positioning screws on each side and a locking mechanism at the end. The pressure and extent of the positioning screws may be varied somewhat thereby permitting each of the tools to be rearranged and articulated to a degree within the machine. Other machines employ similar, but not identical, methods for aligning the tools. For example, the Bobst.RTM. center line method is well known in the art and comprises a series of alignment notches on the tool and corresponding pegs interposed on the machine frame for initially centering the tool. This centering mechanism nonetheless permits the tool to be articulated in the directions necessary to achieve alignment. All of these methods, and others not disclosed here, are well-known in the art and are equally adaptable for use with the instant invention.
The invention contemplates, however, that the operator will generally align each of the tools using a test sheet and the locking and adjustment screws or other alignment means of the machine for each step of the process. For example, in the prior art, an operator will cut a single sheet as a sample and urge the sheet onto the female stripping tool. The operator will then adjust the female stripping tool "by eye" using the available adjustment means, whether the Bobst.RTM. center line system or other systems, so that the cut sheet is properly interposed over the female stripping tool. Even this initial step is usually very time consuming since the operator must carefully insure the female stripping tool is aligned with the cut sheet. Small adjustments in the alignment means must be made by hand and the results reviewed until the operator is satisfied the female stripping tool is properly aligned with the die cut sheet. The operator must then repeat the entire procedure by lowering the male stripping tool over the female stripping tool to insure engagement is precise and does not affect or damage the cut sheet. Again, the male stripping tool is positioned using the eyes of the operator and the particular manual alignment means available on the machine at hand. After the stripping station is properly aligned, i.e., after each of the female stripping tool, male stripping tool and die cut sheet are aligned for proper engagement, the operator continues set-up of the machine by urging a test sheet over the female blanking tool at the next stage of the process. The time consuming and exact steps employed for the stripping portion of the process are repeated, verbatim, for the blanking operation. The operator by hand and through an eye view of the components insures their alignment and complete set-up of the machine.
Accordingly, it is well known and recognized in the prior art that set-up of the box blank cutting machine is critical to efficient and proper automatic cutting, stripping and blanking of multiple box blanks. The alignment method currently practiced in the art is a manual one relying upon the senses and vision of the operator in manual adjustment of the stripping and blanking tools through use of the applicable alignment means of a particular machine press. Accordingly, it is not unusual for machine set-up to take anywhere from four to six hours, especially for complex box layouts comprising various series of boxes and orientations. On account of the precision required and the high tolerances of the components, the method of manually setting up the machine may require that the machine be "down" for extended periods of time between production runs. This, of course, results in diminished capacity and productivity and affects the overall cost of production and price of the box blanks.
Accordingly, the present invention contemplates a set-up and alignment method for automatic box blank die-cutting machines that greatly reduces the set-up time by minimizing burdensome requirements on the operator and instead, employs a series of specially configured tools and alignment devices adapted to quickly and easily insure precise and accurate alignment of the system components. This improved method of alignment and set-up, in turn, reduces "down time" dramatically, increases productivity and ultimately lowers the production cost of the resulting die-cut box blanks.